Fast weight loss diets normally work by having you simply eat a lot less than you usually do and keeping your fat intake to an absolute minimum. Other fast weight loss diets tell you to just eat certain foods or drink juices until you reach a weight you're comfortable with.

When you attempt to lose weight with fast weight loss diets by making radical changes in your eating habits and going from consuming thousands of calories a day to far less calories, it is inevitable that you will you see the number on your scale go down. The question to ask yourself is what are you actually losing on this seemingly effective fast weight loss diet?

You see, losing weight is one thing but losing fat is another. The difference is that when you simply lose weight, this could be water weight, muscle tissue or body fat. However, while fast weight loss diets often help you lose weight, rarely will you be losing much body fat.

What's more, as a result of the loss of muscle tissue, your body burns fewer calories every day, since muscle uses up lots of calories by itself. This means that fast weight loss diets will make it even easier than before to gain weight. This is why the majority of dieters, especially those on fast weight loss diets, put the weight they lost back on, and often gain more weight, after going back to their old eating habits.

Another disadvantage of fast weight loss diets which tell you to drastically drop your calories is that after your body immediately responds by losing weight initially the weight loss will slow down to a halt. This is because your body is made to survive, and when you suddenly stop eating as much as normal, it holds on to your body fat since one of the purposes of fat is to fuel your body when you don't have enough energy coming from food.

As a result of all this, you will find that pretty soon you will go back on another fast weight loss diet to lose all the weight you packed back on. This is where the concept of yo-yo dieting came from and one of the signs of such behaviour is flabby upper arms which is a result of the loss of muscle tissue. One study found that going on fast weight loss diets frequently can weaken the immune system and even increase your chances of developing cancer.

Fast weight loss diets also focus a lot on what you eat but very little on why you get fat. The truth is that many of us do not get anywhere near the amount of exercise that we should, and when you also take into account how much food we eat, and the high levels of sugar and fat we consume, it's no surprise that almost 35% of Americans are obese. However, it is very difficult to gather the energy to exercise at a moderate pace since fast weight loss diets are usually low-calorie diets.

Rather then resort to fast weight loss diets, I recommend focusing on eating small and frequent healthy meals to avoid fat gain, and implement an exercise program involving both aerobic exercise and strength/resistance training to burn the fat and build muscle so your body burns more calories at rest. A fast weight loss diets will have the opposite effect and is a very unhealthy way to lose fat.